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Display Randomly Goes Black


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#1 Astral7

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Posted 06 February 2012 - 06:12 PM

I have a Toshiba Qosmio F45. Last month I replaced the power jack and this is when it started happening. After I replaced the power jack the laptop would load and get to the desktop but then after about 10mins it turned black. I tried hooking it up to my desktop display but after about a minute or two it would switch back to the laptop display and I wouldn't be able to switch it back.

I went onto the internet to do some research and after asking around I figured that the it must of been the back light or the inverterboard. So I went and replaced those two parts but it keeps happening. It always goes black after a random amount of time but what is strange is that when my laptop tried to do the start up repair it didn't go black until it was finished. It stayed on during the whole repair process.

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#2 James Litten

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Posted 06 February 2012 - 06:43 PM

I imagine that you probably already tried this but have you seen if it happens when you run the laptop from the battery with nothing plugged into the power jack? If not, that might isolate the problem.

The power to the screen is separated from the power to the computer right away so it is quite possible for one to have power problems while the other does not. If the battery works then it is probably a partial problem with the jack install with the connection to the screen's power circuit.

James

#3 Astral7

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Posted 06 February 2012 - 07:30 PM

My battery has been dead for some time now so I won't be able to try that.

#4 James Litten

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Posted 06 February 2012 - 07:50 PM

I hate to say this because I've been in your shoes more than once but you might want to consider reinstalling the jack or at least taking a real good look at the solder job.

What might and I mean MIGHT be happening is that after the connection heats up a little bit, the connection where the jack is attached that sends voltage to the screen is expanding a little bit apart and it is dropping the voltage going to the inverter enough that it can't power up the screen. That would explain the randomness of the blackouts. That fluctuation in voltage might cause it to change from external display back to laptop screen too but I'm not sure how that circuit works.

When it blacks out, have you tried shining a flashlight on it to see if the LCD is still displaying properly and it's just the light going out? It can be hard to see on some laptops.

James

#5 Astral7

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Posted 07 February 2012 - 12:06 AM

I'm really an amateur at this so I can't really tell if the solder job is good or not. I just ordered the part off of ebay and followed a guide to install it. How can I tell if the the solder job is bad?

I've used a flashlight when it went black and I was able to see that it is still displaying.

#6 James Litten

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Posted 07 February 2012 - 12:42 AM

This is how you become a pro :)

I'll look for some specs and maybe pictures of the jack placement and pins then I'll post some tips for you tomorrow.

James

#7 James Litten

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Posted 07 February 2012 - 10:17 AM

I pulled up some information on that jack. It has a connector and doesn't need to be soldered, is that what you have?

I wish more power jacks were like that :)

That makes this much more easy. You want to look at the connectors for the power jack and the inverter (don't get shocked!). Make sure that they are connected properly, look inside the holes to make sure the metal makes good contact with each other when they are connected, make sure that there aren't any hard bends or kinks in the wires where the wire might be breaking inside the insulation. If you have a continuity checker or Ohm meter, check the jack to make sure the pins are connected to the post and the ground of the jack. While doing this wiggle the wires a little bit and make sure it maintains continuity. Put it all back together and see what happens.

James

Edited by NeverSayDie, 07 February 2012 - 10:18 AM.





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